International peace envoy Kofi Annan is meeting with Chinese officials in Beijing as he tries to secure further support for his proposal to end violence in Syria, after winning the full backing of Russia.

The U.N. and Arab League envoy visited China's Foreign Ministry Tuesday, and is scheduled to meet with Premier Wen Jiabao later in the day.

Annan has proposed a six-point plan to Syrian President Bashar al-Assad calling on government forces and rebels to agree on a cease-fire and engage in dialogue. The blueprint, endorsed by the U.N. Security Council, does not include a Western and Arab demand for Assad to resign - a requirement that Russia and China oppose.

U.S. State Department spokeswoman Victoria Nuland said Monday the council's endorsement last week was a "very good step." She said the goal now is to make clear to Assad that he longer has "friends" to "protect him from the demands of the international community."

In Syria Monday, government security forces killed at least 19 people in attacks across the country,

Activists said government shells hit several parts of the central city of Homs as part of a daily assault on remaining centers of resistance. They said Assad's forces also carried out arrest raids throughout the country. Their reports could not be independently confirmed because Syria tightly restricts foreign reporting.

Meanwhile, Turkey suspended operations at its Damascus embassy, citing Syria's worsening security situation. Ankara's move further isolates President Assad and follows a recent series of embassy closures by Arab and Western nations critical of his violent crackdown on the revolt. Norway also said it is closing its embassy.

In Istanbul, Syrian opposition groups gathered Monday in a last-ditch attempt at forging a united front before a major conference April 1. Western and Arab nations calling themselves the "Friends of Syria" are due to meet in the Turkish city to discuss support for the Syrian opposition's struggle to end decades of autocratic rule.

U.S. Secretary of State Hillary Clinton will attend the conference after meeting Saudi Arabia's King Abdullah and foreign ministers of five Gulf Arab states in Riyadh later this week. The State Department said Clinton's efforts at both gatherings will focus on ending Syria's bloodshed.

Also Monday, one of three investigators on a U.N. panel documenting crimes against humanity in Syria - including executions and torture - resigned in protest of the Syrian government's refusal to let them into the country. Yakin Erturk, a leading international rights expert, made clear her resignation is not a criticism of the panel, which she said has done everything possible to establish the kinds of crimes Mr. Assad's forces have committed over the past year.

Syria's state news agency SANA said the country's parliament has called on Mr. Assad to consider delaying parliamentary elections scheduled for May 7 in order to allow for the outcome of a "national dialogue."

The election is part of what the government calls a series of reforms based on a new constitution approved by referendum in February.

The United Nations says more than 8,000 people have been killed in the Syrian government's crackdown on the uprising during the past year. Damascus blames the violence on what it says are foreign-backed terrorists.